Hydraulic actuators are known for operating motor vehicle clutches and other mechanism at a remote location by way of a master cylinder and slave cylinder combination. The master cylinder is operated, for example, by the clutch pedal, and the slave cylinder is connected to the clutch via a throwout bearing. The master and slave cylinders are interconnected by a high-pressure line or conduit. Depressing the clutch pedal displaces the piston in the master cylinder to close a passage or port between the master cylinder fluid chamber and a fluid reservoir, and to pressurize the connection to the slave cylinder. Displacement of the piston in the slave cylinder disengages the clutch.
It is also known to preassemble and prefill apparatus of this type before shipment of the assembly to a motor vehicle manufacturer for installation on the motor vehicle. The motor vehicle manufacturer need only fix the master and slave cylinders in place and make simple mechanical connections to the clutch pedal and clutch bearing. See U.S. Pat. No. 4,599,860 "Liquid Pressure Apparatus" issued July 15, 1986 to David Parsons and assigned to Automotive Products, plc of Warwickshire, England.
The hydraulic system shown in the aforementioned Parsons patent discloses a fluid reservoir which is integral with the master cylinder and which is dedicated exclusively to the clutch actuator. Prefilled and preassembled hydraulic actuator apparatus of this type have achieved wide acceptance, particularly in the automotive industry, because of the ease of installation in the motor vehicle, because of their extremely reliable operation over long periods of time and because of their ability to automatically compensate for wear.
There are situations in which it is desirable to employ such prefilled hydraulic actuator apparatus in a system utilizing a detached reservoir; such a reservoir may, for example, supply fluid both to the preassembled and prefilled hydraulic clutch actuator and to another system on the vehicle such as the brake system.